New Seat Details - Battersea and Clapham

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Battersea and Clapham been in force at that time. The basic idea of the calculation is to look at the district council wards which make up the new seat, and estimate how they voted in 2017. This estimate is based on the recent local election results in those wards, with adjustments made to allow for different turnouts and different voting patterns for local and general elections.

In many cases, wards are divided between several old constituencies or between new constituencies. So the same ward may be shown more than once, but the electorate shown will reflect that ward sub-section.

Election results from a recent local election are given. This is usually the local election closest to 2015 from the period 2012-2015. For multiple-member wards, the votes shown are the sum of the votes cast for all candidates of each party. A negative number indicates candidate(s) elected unopposed.

Calculation method

There are two problems with using the raw (actual) local election results to imply general election results ward-by-ward. Firstly, turnout can be different between local and general elections, which means that the total number of local votes cast does not equal the number of votes cast in each old seat at the general election. To correct for this, we adjust the local votes to match the general election turnout. Each ward's result is scaled, whilst keeping constant the percentage support for each party, so that the total turnout adds up to the old seat's general election turnout. All wards in the old seat are assumed to have the same percentage turnout.

Party	Implied 2017 Votes	Implied 2017 Share
LAB	30,398	51.6%
CON	21,207	36.0%
LIB	4,837	8.2%
Green	1,114	1.9%
MIN	901	1.5%
UKIP	337	0.6%
OTH	68	0.1%
LAB Majority	9,191	15.6%

Secondly, even though we now have the correct number of votes in the old seat, the party totals will not match the general election result. Some parties do better at the local election than the general election, and others do vice versa. We call these strong and weak parties respectively. The next step is to transfer votes from strong parties to weak parties. This is done by taking votes proportionally away from strong parties and putting them in a transfer pool. For instance if a party got 12,500 local votes, but only 10,000 general election votes, it will lose 20% over all the wards. These votes in each ward will be put in the ward's transfer pool and allocated to the weak parties. Weak parties will get votes transferred to them in proportion to the votes they need over the old seat. For instance, if two weak parties need 4,000 and 1,000 votes respectively, the first party will get 80% of each ward's transfer pool and the second party will get 20% of each ward's transfer pool. The transfer of votes between parties is done using the Electoral Calculus Transition Model.

Battersea and Clapham: Map

List of old seats forming part of Battersea and Clapham

Old seat: Battersea

The table shows the transfer-adjusted results for each ward in the old seat of Battersea, as well as showing which new seat each ward is in.

Old seat: Battersea				Transfer-adjusted Results
District	Ward	Electorate 2017	New Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	NAT Votes	MIN Votes	OTH Votes	Total Votes
Wandsworth	Balham	10,443	Tooting and Balham	3,501	3,068	730	42	121	0	160	4	7,626
Wandsworth	Fairfield	9,986	Putney and Wandsworth Town	3,310	3,143	706	47	119	0	174	5	7,504
Wandsworth	Latchmere	9,569	Battersea and Clapham	2,214	4,839	514	69	116	0	205	5	7,962
Wandsworth	Northcote	9,292	Battersea and Clapham	3,672	2,879	767	40	124	0	152	4	7,638
Wandsworth	Queenstown	9,948	Battersea and Clapham	3,113	4,377	558	70	129	0	177	5	8,429
Wandsworth	Shaftesbury	9,921	Battersea and Clapham	3,251	3,244	555	24	116	0	138	4	7,332
Wandsworth	St Mary's Park	10,765	Battersea and Clapham	3,816	3,743	571	65	140	0	229	6	8,570
	Total	69,924		22,877	25,293	4,401	357	865	0	1,235	33	55,061

The full details of these calculations are given on the Battersea seat details page. Click on "Show workings".

Old seat: Streatham

The table shows the transfer-adjusted results for each ward in the old seat of Streatham, as well as showing which new seat each ward is in.

Old seat: Streatham				Transfer-adjusted Results
District	Ward	Electorate 2017	New Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	NAT Votes	MIN Votes	OTH Votes	Total Votes
Lambeth	Brixton Hill	9,625	Streatham and Brixton Hill	1,363	5,582	440	58	255	0	0	0	7,698
Lambeth	Clapham Common	8,296	Battersea and Clapham	2,194	3,467	372	29	176	0	0	0	6,238
Lambeth	St Leonard's	8,684	Streatham and Brixton Hill	1,654	4,584	561	45	217	0	0	0	7,061
Lambeth	Streatham Hill	9,010	Streatham and Brixton Hill	1,389	4,652	593	53	221	0	0	0	6,908
Lambeth	Streatham South	8,241	Streatham and Brixton Hill	1,588	4,824	337	35	188	0	0	0	6,972
Lambeth	Streatham Wells	8,830	Streatham and Brixton Hill	1,450	4,920	585	58	221	0	0	0	7,234
Lambeth	Thornton	8,078	Battersea and Clapham	1,199	4,280	330	40	177	0	0	0	6,026
Lambeth	Tulse Hill	9,522	Streatham and Brixton Hill	1,090	5,904	393	32	240	0	0	0	7,659
	Total	70,286		11,927	38,213	3,611	350	1,695	0	0	0	55,796

The full details of these calculations are given on the Streatham seat details page. Click on "Show workings".

Old seat: Vauxhall

The table shows the transfer-adjusted results for each ward in the old seat of Vauxhall, as well as showing which new seat each ward is in.

Old seat: Vauxhall				Transfer-adjusted Results
District	Ward	Electorate 2017	New Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	NAT Votes	MIN Votes	OTH Votes	Total Votes
Lambeth	Bishop's	6,094	Brixton and Vauxhall	811	2,242	1,498	0	97	0	0	38	4,686
Lambeth	Clapham Town	9,187	Battersea and Clapham	1,748	3,569	1,170	0	136	0	0	44	6,667
Lambeth	Ferndale	9,382	Brixton and Vauxhall	1,312	4,332	1,277	0	150	0	0	104	7,175
Lambeth	Larkhall	10,139	Brixton and Vauxhall	1,649	4,926	1,503	0	172	0	0	100	8,350
Lambeth	Oval	8,870	Brixton and Vauxhall	1,230	4,076	1,768	0	161	0	0	81	7,316
Lambeth	Prince's	9,813	Brixton and Vauxhall	1,263	4,003	1,327	0	150	0	0	130	6,873
Lambeth	Stockwell	8,434	Brixton and Vauxhall	1,192	4,281	1,447	0	144	0	0	93	7,157
Lambeth	Vassall	9,439	Brixton and Vauxhall	1,071	4,146	1,335	0	142	0	0	120	6,814
	Total	71,358		10,276	31,575	11,325	0	1,152	0	0	710	55,038

The full details of these calculations are given on the Vauxhall seat details page. Click on "Show workings".

New seat: Battersea and Clapham

District	Ward	Electorate 2017	Old Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	NAT Votes	MIN Votes	OTH Votes	Total Votes
New seat: Battersea and Clapham
Lambeth	Clapham Common	8,780	Streatham	2,194	3,467	372	29	176	0	0	0	6,238
Lambeth	Clapham Town	9,921	Vauxhall	1,748	3,569	1,170	0	136	0	0	44	6,667
Lambeth	Thornton	8,480	Streatham	1,199	4,280	330	40	177	0	0	0	6,026
Wandsworth	Latchmere	11,218	Battersea	2,214	4,839	514	69	116	0	205	5	7,962
Wandsworth	Northcote	10,760	Battersea	3,672	2,879	767	40	124	0	152	4	7,638
Wandsworth	Queenstown	11,876	Battersea	3,113	4,377	558	70	129	0	177	5	8,429
Wandsworth	Shaftesbury	10,329	Battersea	3,251	3,244	555	24	116	0	138	4	7,332
Wandsworth	St Mary's Park	12,074	Battersea	3,816	3,743	571	65	140	0	229	6	8,570
	Total	83,438		21,207	30,398	4,837	337	1,114	0	901	68	58,862

And these are the implied results for 2017 for the new seat of Battersea and Clapham. Please note that the wards used are those of 2015 in order to be consistent with those used by the Boundary Commissions.

Implied MP at 2017:	Marsha De Cordova (LAB)
County/Area:	Wandsworth (London)
Electorate:	83,438
Turnout:	70.5%

Battersea and Clapham: New Boundaries 2018 Calculation

Battersea and Clapham: Overview

Introduction